1. Technical Field of the Invention
The present invention relates to novel N-aryl-2-hydroxyalkylamide compounds, to a process for the synthesis thereof, and to the formulation of at least one of said novel compounds into cosmetic/therapeutic compositions well suited for inducing and/or stimulating hair growth and/or retarding hair loss and/or for treating hyperseborrhoea and/or acne.
2. Description of the Prior Art
In human subjects the growth of the hair and its renewal are principally determined by the activity of the hair follicles. This activity is cyclical and essentially comprises three phases, namely, the anagen phase, the catagen phase and the telogen phase.
The active anagen phase, or growth phase, which lasts for several years and during which the hairs lengthen, is succeeded by a very short and transitory catagen phase, which lasts for a few weeks, and then by a resting or quiescent phase, also designated the telogen phase, which lasts for a few months.
At the end of the rest period, the hairs fall out and another cycle begins anew. The head of hair is thus continuously renewed and, out of the approximately 150,000 hairs on a human head, at each instant approximately 10% of them are at rest in the telogen phase and will thus be replaced in a few months.
However, various causes and challenges can result in a significant, temporary or definitive, loss of hair. Alopecia is essentially due to a disruption in hair renewal which initially gives rise to an acceleration of the frequency of the cycles at the expense of the quality of the hairs and then of their quantity. A progressive thinning of the head of hair takes place by regression of the so-called "terminal" hairs to the down stage. Certain regions are preferentially affected, in particular the temporal or frontal bulbs in man and, in woman, a diffuse alopecia of the vertex is observed.
By the term "alopecia" is intended an entire family of conditions of the hair follicle having as final consequence the partial or general definitive loss of the hair.
In a significant number of cases, early hair loss occurs in subjects who are genetically predisposed and it affects men in particular. It is more particularly androgenetic or androgenic alopecia or, alternatively, androgeno-genetic alopecia.
Compositions that eliminate or reduce the effects of alopecia and, in particular, that induce or stimulate hair growth or decrease hair loss have long been considered desiderata in the cosmetic and pharmaceutical industries.
In this regard, a large number of very diverse active compounds have been suggested for such purposes, for example, 2,4-diamino-6-piperidinopyrimidine 3-oxide or "Minoxidil" described in U.S. Pat. Nos. 4,139,619 and 4,596,812 or numerous derivatives thereof, such as those described, for example, in EP-0,353,123, EP-0,356,271, EP-0,408,442, EP-0,522,964, EP-0,420,707, EP-0,459,890 and EP-0,519,819.